线程范围内数据共享

最新推荐文章于 2025-07-11 00:07:27 发布

原创最新推荐文章于 2025-07-11 00:07:27 发布 · 150 阅读

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#java

JAVA多线程同时被 2 个专栏收录

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本文探讨了Java中线程范围内数据共享的方法，通过Thread类与HashMap结合实现多模块间的值传递，并对比ThreadLocal类在创建对象时确保同一线程同一对象的特性，通过实例展示了其在多线程环境中的应用。

java实现线程范围内数据共享：
Thread.crruntThread()
使用HashMap<Thread,Object>

经过A,B,C三个模块都是获得同一个值

public class ThreadDemo20 {
	private static HashMap<Thread,Integer> data=new HashMap<Thread,Integer>();

	static class A{
		public void getData(){
			Thread t=Thread.currentThread();
			int value=data.get(t);
			System.out.println(t.getName()+" from A getData "+value);
		}
	}
	static class B{
		public void getData(){
			Thread t=Thread.currentThread();
			int value=data.get(t);
			System.out.println(t.getName()+" from B getData "+value);
		}
	}
	static class C{
		public void getData(){
			Thread t=Thread.currentThread();
			int value=data.get(t);
			System.out.println(t.getName()+" from C getData "+value);
		}
	}

	public static void main(String[] args) {
		for (int i = 0; i < 2; i++) {
			new Thread(new Runnable() {
				@Override
				public void run() {
					int value=new Random().nextInt(1000);
					data.put(Thread.currentThread(), value);
					A a1=new A();
					a1.getData();
					B b1=new B();
					b1.getData();
					C c1=new C();
					c1.getData();
				}
			}).start();;
		}
	}
}

执行结果

Thread-1 from A getData 521
Thread-1 from B getData 521
Thread-1 from C getData 521
Thread-0 from A getData 925
Thread-0 from B getData 925
Thread-0 from C getData 925

java中提供了Threadlocal类已经实现了该
Threadlocal<Integer> tl=new Threadlocal<Integer>()
t1.get();
[b]使得该类在创建对象时候直接就是同一个线程同一个对象对象不同线程不同，就像你登录后获得你的当前登录的用户时候不会获得别人的用户[/b]
[b]来点实际的：[/b]

public class UserService {

	private static ThreadLocal<UserService> tl = new ThreadLocal<UserService>();

	private UserService() {}

	public static UserService getInstance() {
		UserService us = tl.get();
		if (us == null) {
			us = new UserService();
			tl.set(us);
		}
		return us;
	}

}

这个大家应该再熟悉不过了。我们使用多个线程来测试一下

public class UserServiceTest {

	public static void main(String[] args) {
		for (int i = 0; i < 4; i++) {
			new Thread(new Runnable() {
				@Override
				public void run() {
					A a=new A();
					a.print();
					B b=new B();
					b.print();
				}
			}).start();
		}
	}

	static class A {
		public void print() {
			UserService us = UserService.getInstance();
			System.out.println("from A "+Thread.currentThread().getName() + "..." + us);
		}
	}

	static class B {
		public void print() {
			UserService us = UserService.getInstance();
			System.out.println("from B "+Thread.currentThread().getName() + "..." + us);
		}
	}
}

测试结果是:同一个线程的UserService是相同的，不论是在A或者B中都能够获得

from A Thread-3...thread.UserService@787d6a
from A Thread-0...thread.UserService@1f4cbee
from A Thread-1...thread.UserService@1f4cbee
from A Thread-2...thread.UserService@787d6a
from B Thread-2...thread.UserService@787d6a
from B Thread-3...thread.UserService@787d6a
from B Thread-0...thread.UserService@1f4cbee
from B Thread-1...thread.UserService@1f4cbee